A driver may increase a torque demand to accelerate a vehicle. Although the driver may wish for immediate torque production, a vehicle powertrain may develop the requested torque over time. For example, a powertrain that includes a turbocharged engine may increase torque output over several seconds after an increase in driver-demanded powertrain torque. Output of the turbocharged engine may increase as turbocharger compressor speed increases, and it may take several seconds for the compressor to achieve a speed where a desired amount of boost is provided to the engine. However, engine output may eventually provide the requested torque. Some drivers may become impatient and further increase the torque demand in an attempt to achieve the desired torque sooner. The increased torque demand may initiate a transmission downshift to provide the requested torque. Yet, the downshift may decrease vehicle fuel economy and increase shift busyness even though the powertrain may have provided the desired torque absent the downshift if the vehicle had been allowed to accelerate for a short time longer before the downshifting commenced.
The inventors herein have recognized the above-mentioned issue and have developed a driver feedback method, comprising: increasing accelerator pedal application resistance in response to a decreasing difference in available powertrain torque and desired powertrain torque.
By increasing accelerator pedal application resistance in response to a decreasing difference between available powertrain torque (e.g., maximum powertrain torque at the present powertrain speed) and desired powertrain torque, it may be possible to provide feedback to a vehicle's driver that a further increase in desired torque may result in a transmission downshift or that the desired demand torque may be provided if the driver shows a small amount of patience. For example, application resistance of an accelerator pedal may be increased to require a driver to apply more force to request higher demand torques as driver-demanded powertrain torque increases and approaches an available powertrain torque. In some examples, the application resistance of the accelerator pedal may be further increased as driver-demanded powertrain torque approaches a torque where a transmission in the powertrain is downshifted. In this way, the driver may be notified that a downshift will occur if the driver continues to increase the demand torque. The driver may then show patience and reduce the rate of driver-demanded powertrain torque increase, or alternatively, the driver may continue to increase driver demand and expect a transmission downshift to increase vehicle acceleration.
In other examples, accelerator pedal application resistance to motion may be increased in response to an increasing difference between actual powertrain torque (e.g., actual torque delivered by the powertrain) and desired powertrain torque (e.g., powertrain torque that is demanded by a driver, for example). By increasing accelerator pedal application resistance to motion in response to an increasing difference between actual powertrain torque and desired powertrain torque, accelerator pedal resistance may be selectively increased during conditions where actual powertrain torque lags desired powertrain torque. In this way, the driver may be notified that additional powertrain torque may be produced at the present driver-demanded powertrain torque provided the driver shows a small amount of patience.
The present description may provide several advantages. In particular, the approach may provide reduced shift busyness. Further, the approach may improve a driver's perception of the vehicle driving experience by providing the driver enhanced vehicle feedback. Further still, the approach may be useful for training a driver to better distinguish between driving for performance and driving for fuel economy.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.